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8 October 1999 Anomalous drain current-voltage characteristics in AlGaN/GaN MODFETs at low temperatures
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This paper reports the observation of defect-related anomalous low temperature drain current-voltage characteristics in AlGaN/GaN MODFETs. We have performed our study on devices with a relatively large number of lattice defects, generally referred to as nanopipes, in their active area. The observed low temperature anomalies appear as 'kinks' in the Ids-Vds characteristics and are observable at temperatures < 210 K. In a device with a large density of defects, we observe current collapse and large threshold voltage shifts at 80 K, which depend on bias history. We attribute the observed behavior to impact ionization of charge accumulated in the AlGaN layer by high- energy electrons injected from the 2DEG via real space transfer. The existence of these mechanisms indicates that device self-heating is not the solely responsible for the negative differential resistance at high electric fields in AlGaN/GaN MODFETs. These mechanisms may have significant influence on the high frequency performance of power transistors and on our current understanding of high electric field parallel transport phenomena in III-nitride heterojunctions.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gilberto A. Umana-Membreno, John M. Dell, Lorenzo Faraone, Yi-Feng Wu, Giacinta Parish, and Umesh K. Mishra "Anomalous drain current-voltage characteristics in AlGaN/GaN MODFETs at low temperatures", Proc. SPIE 3893, Design, Characterization, and Packaging for MEMS and Microelectronics, (8 October 1999);

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